A high-pressure fluorine-containing polyether gel polymer electrolyte and a preparation method and application thereof

Abstract

The application provides a high-voltage fluorine-containing polyether gel polymer electrolyte and a preparation method and application thereof. The high-voltage fluorine-containing polyether gel polymer electrolyte comprises a fluorine-containing polyether-based polymer, and the fluorine-containing polyether-based polymer is obtained through in-situ polymerization of pentaerythritol tetraacrylate monomers, polyethylene glycol monomethyl ether methacrylate monomers and 2-(perfluorobutyl) ethyl methacrylate monomers; the high-voltage fluorine-containing polyether gel polymer electrolyte has the advantages of a wide electrochemical window, high ionic conductivity, high lithium ion transference number and good interface stability; a high-voltage lithium ion battery prepared by using the high-voltage fluorine-containing polyether gel polymer electrolyte has excellent cycle stability at a high cut-off voltage, and the service life is significantly prolonged. In addition, the preparation process of the high-voltage fluorine-containing polyether gel polymer electrolyte is simple, raw materials are easy to obtain, and the high-voltage fluorine-containing polyether gel polymer electrolyte is suitable for large-scale production and has a wide market application prospect in the field of high-voltage lithium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of gel electrolyte preparation technology, and in particular to a high-pressure fluorinated polyether gel polymer electrolyte, its preparation method and application. Background Technology

[0002] With the increasing demands for energy density and safety of high-voltage lithium-ion batteries from new energy electric vehicles and large-scale energy storage technologies, developing solid-state electrolyte systems that match high-voltage cathode materials (such as NCM811 and lithium-rich manganese cathode materials) has become crucial. Gel electrolytes (GPEs) have attracted much attention due to their combination of the high ionic conductivity of liquid electrolytes and the safety of solid electrolytes. Among them, polyether-based gel electrolytes have become a research hotspot due to their advantages such as chain segment flexibility and good electrode interface contact. However, most polyether-based gel electrolytes face two major challenges:

[0003] Poor antioxidant capacity: The terminal hydroxyl groups and ether oxygen chains of polyether polymers are prone to oxidative decomposition under high voltage, resulting in a narrow electrochemical window of the electrolyte (usually <4V), making it difficult to adapt to high-voltage cathodes and limiting the improvement of energy density of high-voltage lithium-ion batteries.

[0004] Slow ion transport kinetics and poor interface stability: Due to the strong solvation structure of ether-oxygen groups with lithium ions, anions can move freely, resulting in a low lithium ion transference number (usually <0.3). At high rates, this easily leads to severe concentration polarization, exacerbates the growth of lithium dendrites, damages the electrolyte, and thus causes performance degradation and reduced safety of high-voltage lithium-ion batteries.

[0005] Therefore, developing a high-pressure polyether-based gel electrolyte that combines a wide electrochemical window, high lithium-ion transference number, and good interfacial stability is a pressing technical problem that needs to be solved. Summary of the Invention

[0006] This invention provides a high-voltage fluorinated polyether gel polymer electrolyte, which possesses both a wide electrochemical window (4.6V) and high ionic conductivity (1.61mS / cm). 2 High lithium-ion transference number (t) Li + With a strength of 0.85 and good interface stability, it can be adapted to high-voltage cathodes; high-voltage lithium-ion batteries prepared using this high-voltage fluorinated polyether gel polymer electrolyte exhibit excellent cycle stability at high cutoff voltages and significantly extended lifespan.

[0007] This invention also provides a method for preparing a high-pressure fluorinated polyether gel polymer electrolyte, which can be obtained by means of the above-mentioned high-pressure fluorinated polyether gel polymer electrolyte having a wide electrochemical window, high ionic conductivity, high lithium ion transference number and good interfacial stability.

[0008] This invention also provides a high-voltage lithium-ion battery comprising the above-mentioned high-voltage fluorinated polyether gel polymer electrolyte. Research by this invention shows that the high-voltage lithium-ion battery prepared using the above-mentioned high-voltage fluorinated polyether gel polymer electrolyte exhibits excellent cycle stability and significantly extended lifespan at high cutoff voltages.

[0009] A first aspect of the present invention provides a high-pressure fluorinated polyether gel polymer electrolyte, comprising a fluorinated polyether-based polymer and a lithium salt and an organic solvent dispersed in the fluorinated polyether-based polymer;

[0010] The fluorinated polyether-based polymer is obtained by in-situ polymerization of pentaerythritol tetraacrylate monomer, polyethylene glycol monomethyl ether methacrylate monomer and 2-(perfluorobutyl)ethyl methacrylate monomer.

[0011] In the high-pressure fluorinated polyether gel polymer electrolyte described above, the mass ratio of the pentaerythritol tetraacrylate monomer, the polyethylene glycol monomethyl ether methacrylate monomer, and the 2-(perfluorobutyl)ethyl methacrylate monomer is 2:1:2.

[0012] The high-pressure fluorinated polyether gel polymer electrolyte described above has a molecular weight of 200-400 g / mol for the polyethylene glycol monomethyl ether methacrylate monomer.

[0013] A second aspect of the present invention provides a method for preparing a high-pressure fluorinated polyether gel polymer electrolyte, comprising the following steps:

[0014] (1) Dissolve lithium salt in an organic solvent to prepare a lithium salt solution;

[0015] (2) The lithium salt solution, pentaerythritol tetraacrylate monomer, polyethylene glycol monomethyl ether methacrylate monomer, 2-(perfluorobutyl)ethyl methacrylate monomer and thermal initiator are mixed to obtain a precursor solution;

[0016] (3) The precursor solution is heated to carry out in-situ polymerization to obtain the high-pressure fluorinated polyether gel polymer electrolyte.

[0017] In the preparation method of the high-pressure fluorinated polyether gel polymer electrolyte as described above, in step (1), the lithium salt is lithium hexafluorophosphate, and the organic solvent is at least one of diethyl carbonate, dimethyl carbonate, ethylene carbonate, and fluoroethylene carbonate.

[0018] The lithium salt solution has a lithium salt concentration of 1 mol / L.

[0019] In the preparation method of the high-pressure fluorinated polyether gel polymer electrolyte as described above, in step (2), the mass ratio of the lithium salt solution, the pentaerythritol tetraacrylate monomer, the polyethylene glycol monomethyl ether methacrylate monomer and the 2-(perfluorobutyl)ethyl methacrylate monomer is 45:2:1:2.

[0020] In the preparation method of the high-pressure fluorinated polyether gel polymer electrolyte as described above, in step (2), the molecular weight of the polyethylene glycol monomethyl ether methacrylate monomer is 200-400 g / mol.

[0021] In the preparation method of the high-pressure fluorinated polyether gel polymer electrolyte as described above, in step (2), the thermal initiator is azobisisobutyronitrile;

[0022] The mass ratio of the thermal initiator to the pentaerythritol tetraacrylate monomer is (0.2-0.3):2.

[0023] In the preparation method of the high-pressure fluorinated polyether gel polymer electrolyte as described above, in step (3), the heating temperature is 55-65℃ and the time is 8-12 hours.

[0024] A third aspect of the present invention provides a high-voltage lithium-ion battery, comprising the high-voltage fluorinated polyether gel polymer electrolyte or the high-voltage fluorinated polyether gel polymer electrolyte prepared by the preparation method described above.

[0025] The solution of the present invention has at least the following effects:

[0026] The high-voltage fluorinated polyether gel polymer electrolyte provided by this invention comprises a fluorinated polyether-based polymer and lithium salt and organic solvent dispersed in the fluorinated polyether-based polymer. The fluorinated polyether-based polymer is obtained by in-situ polymerization of pentaerythritol tetraacrylate monomer, polyethylene glycol monomethyl ether methacrylate monomer, and 2-(perfluorobutyl)ethyl methacrylate monomer. Pentaerythritol tetraacrylate monomer (PETEA) acts as a crosslinking agent, forming a high-density covalently crosslinked three-dimensional network structure through in-situ polymerization. This provides mechanical properties while effectively locking in solvent molecules, improving the electrochemical and safety performance of the battery. Polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), as a flexible long chain, enhances toughness, and its continuous ether-oxygen groups (-O-) with polar sites react with lithium ions to form a strongly solvated structure, promoting lithium ion dissociation and improving ionic conductivity. 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA) possesses extremely low surface energy and strong hydrophobicity, tending to migrate to the surface during in-situ polymerization. This characteristic promotes homogenization of lithium deposition and effectively inhibits lithium dendrite growth. Furthermore, the 2-(perfluorobutyl)ethyl methacrylate group can regulate the solvation structure between the ether-oxygen group and lithium ions through weak solvation, making it easier for anions to participate in solvation transport and increasing the lithium ion transference number. Simultaneously, the strong electronegativity of the fluorine atom on the 2-(perfluorobutyl)ethyl methacrylate group gives the electrolyte a higher oxidation potential, reducing electrolyte decomposition under high voltage, minimizing interfacial side reactions, and extending battery life. Research in this invention shows that this high-voltage fluorinated polyether gel polymer electrolyte possesses both a wide electrochemical window (4.6V) and high ionic conductivity (1.61 mS / cm). 2 High lithium-ion transference number (t) Li + With a viscosity of 0.85 and good interfacial stability, it is suitable for high-voltage cathodes. High-voltage lithium-ion batteries prepared using this high-voltage fluorinated polyether gel polymer electrolyte exhibit excellent cycle stability and significantly extended lifespan at high cutoff voltages. Furthermore, the preparation process of this high-voltage fluorinated polyether gel polymer electrolyte is simple, the raw materials are readily available, and it is suitable for large-scale production, showing broad market application prospects in the field of high-voltage lithium-ion batteries. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1This is a schematic diagram of the reaction for preparing fluorinated polyether-based polymers according to the present invention;

[0029] Figure 2 These are optical photographs of precursor solution A and high-pressure fluorinated polyether gel polymer electrolyte in Example 1 of the present invention, wherein... Figure 2 A is an optical photograph of precursor solution A. Figure 2 Image B is an optical photograph of a high-pressure fluorinated polyether gel polymer electrolyte;

[0030] Figure 3 This is an optical photograph of the high-pressure fluorinated polyether gel polymer electrolyte adhering to the diaphragm in Application Example 1 of the present invention, wherein... Figure 3 A is an optical photograph without bending. Figure 3 B is an optical photograph taken at a 180° bend.

[0031] Figure 4 The infrared spectroscopy and nuclear magnetic resonance (NMR) results are as follows: Pentaerythritol tetraacrylate monomer (PETEA), polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA), and high-pressure fluorinated polyether gel polymer electrolyte (GPE-F) from Example 1 of this invention, and the polymer electrolyte (GPE) from Comparative Example 2. Figure 4 A represents the infrared spectroscopy test result. Figure 4 B represents the NMR test result;

[0032] Figure 5 The calculation results of the LUMO and HUMO energy levels of each component in the high-pressure fluorinated polyether gel polymer electrolyte in Example 1 of the present invention;

[0033] Figure 6 The lithium-ion batteries in Examples 1-3 of this invention are used at 0.1 mA cm -2 Current density and 0.1 mAh cm⁻¹ -2 Cyclic performance test results under area capacity;

[0034] Figure 7 Cycling diagrams of the lithium-ion batteries in Application Examples 1-3 of this invention under test conditions of 30°C, 1C rate, and a test voltage range of 2.5-4.3V;

[0035] Figure 8 The cycling diagram shows the lithium-ion battery in Application Example 1 of this invention under test conditions of 30°C, 1C rate, and a test voltage range of 2.8-4.5V.

[0036] Figure 9 The circuit diagram shows the lithium-ion battery in Application Example 1 of this invention under test conditions of 30°C, 1C rate, and a test voltage range of 2.8-4.8V. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this art or in accordance with the product instructions. Reagents or instruments used without specified manufacturers are all conventional products that can be obtained commercially.

[0038] It should be noted that the descriptions involving "first," "second," "third," etc. in this invention are used to distinguish similar objects and are not used to describe a specific order or sequence, and therefore should not be construed as limiting the invention.

[0039] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0041] Figure 1 This is a schematic diagram of the reaction for preparing fluorinated polyether-based polymers according to the present invention, as shown below. Figure 1 As shown, a first aspect of the present invention provides a high-pressure fluorinated polyether gel polymer electrolyte, comprising a fluorinated polyether-based polymer and a lithium salt and an organic solvent dispersed in the fluorinated polyether-based polymer; wherein the fluorinated polyether-based polymer is obtained by in-situ polymerization of pentaerythritol tetraacrylate monomer, polyethylene glycol monomethyl ether methacrylate monomer and 2-(perfluorobutyl)ethyl methacrylate monomer.

[0042] The high-voltage fluorinated polyether gel polymer electrolyte provided by this invention has both a wide electrochemical window (4.6V) and high ionic conductivity (1.61mS / cm). 2 High lithium-ion transference number (t) Li + =0.85) and good interface stability; the high-voltage lithium-ion battery prepared using this high-voltage fluorinated polyether gel polymer electrolyte exhibits excellent cycle stability at high cutoff voltage and significantly extended lifespan.

[0043] In this invention, pentaerythritol tetraacrylate monomer (PETEA) serves as a crosslinking agent. Through in-situ polymerization, it forms a high-density covalently crosslinked three-dimensional network structure, providing mechanical properties while effectively locking in solvent molecules, thus improving the electrochemical and safety performance of the battery. Polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), as a flexible long chain, enhances toughness. Furthermore, the polar sites of its continuous ether-oxygen groups (-O-) solvate with lithium ions, forming a strongly solvated structure that promotes lithium ion dissociation and improves ionic conductivity. 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA) has extremely low surface energy and strong hydrophobicity, and tends to migrate to the surface during in-situ polymerization. This characteristic can promote the homogenization of lithium deposition and effectively inhibit the growth of lithium dendrites. Furthermore, the 2-(perfluorobutyl)ethyl methacrylate group can regulate the solvation structure between the ether-oxygen group and lithium ions through weak solvation, making it easier for anions to participate in solvation transport and increasing the lithium ion transference number. At the same time, the strong electronegativity of the fluorine atom on the 2-(perfluorobutyl)ethyl methacrylate group gives the electrolyte a higher oxidation potential, reduces electrolyte decomposition under high voltage, reduces interfacial side reactions, and extends battery life.

[0044] In this invention, the temperature of the above-mentioned in-situ polymerization reaction is 55-65°C and the time is 8-12 hours (h).

[0045] In one specific embodiment, the mass ratio of the pentaerythritol tetraacrylate monomer, the polyethylene glycol monomethyl ether methacrylate monomer, and the 2-(perfluorobutyl)ethyl methacrylate monomer is 2:1:2.

[0046] When the mass ratio of the pentaerythritol tetraacrylate monomer, the polyethylene glycol monomethyl ether methacrylate monomer, and the 2-(perfluorobutyl)ethyl methacrylate monomer meets the above conditions, the monomers are fully polymerized to form a fluorinated polyether polymer. The lithium salt and organic solvent are encapsulated in the gel network structure of the fluorinated polyether polymer, effectively locking in the solvent molecules and avoiding the risk of leakage.

[0047] In one specific embodiment, the molecular weight of the polyethylene glycol monomethyl ether methacrylate monomer is 200-400 g / mol, preferably 320 g / mol.

[0048] When the molecular weight of polyethylene glycol monomethyl ether methacrylate monomer meets the above conditions, it can better cooperate with pentaerythritol tetraacrylate monomer and 2-(perfluorobutyl)ethyl methacrylate monomer to construct a more stable gel network structure, improve the mechanical properties of the electrolyte, and enhance the electrochemical performance and safety performance of the battery.

[0049] A second aspect of the present invention provides a method for preparing a high-pressure fluorinated polyether gel polymer electrolyte, comprising the following steps:

[0050] (1) Dissolve lithium salt in an organic solvent to prepare a lithium salt solution;

[0051] (2) The lithium salt solution, pentaerythritol tetraacrylate monomer, polyethylene glycol monomethyl ether methacrylate monomer, 2-(perfluorobutyl)ethyl methacrylate monomer and thermal initiator are mixed to obtain a precursor solution;

[0052] (3) The precursor solution is heated to carry out in-situ polymerization to obtain the high-pressure fluorinated polyether gel polymer electrolyte.

[0053] In this invention, the in-situ polymerization characteristic benefits from the acrylate groups in each monomer (pentaerythritol tetraacrylate monomer, polyethylene glycol monomethyl ether methacrylate monomer, and 2-(perfluorobutyl)ethyl methacrylate monomer), which can dissolve in lithium salt solution. After being injected into the battery, heating initiates in-situ polymerization, ultimately forming a gel network structure that is in close contact with the electrode surface, namely the high-pressure fluorinated polyether gel polymer electrolyte of this invention. This high-pressure fluorinated polyether gel polymer electrolyte formed by in-situ polymerization achieves molecular-level contact, significantly reducing interfacial impedance. At the same time, the gel network structure in the high-pressure fluorinated polyether gel polymer electrolyte can effectively lock in solvent molecules, avoiding the risk of leakage.

[0054] In one specific embodiment, in step (1), the lithium salt is lithium hexafluorophosphate (LiPF6), and the organic solvent is at least one of diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylene carbonate (EC), and fluoroethylene carbonate (FEC).

[0055] In one specific embodiment, the concentration of the lithium salt in the lithium salt solution is 1 mol / L.

[0056] Furthermore, the lithium salt solution is formulated as 1M LiPF6 in DEC:DMC:EC=1:1:1 Vol% with 10% FEC.

[0057] In one specific embodiment, in step (2), the mass ratio of the lithium salt solution, the pentaerythritol tetraacrylate monomer, the polyethylene glycol monomethyl ether methacrylate monomer, and the 2-(perfluorobutyl)ethyl methacrylate monomer is 45:2:1:2.

[0058] In one specific embodiment, in step (2), the molecular weight of the polyethylene glycol monomethyl ether methacrylate monomer is 200-400 g / mol.

[0059] In one specific embodiment, the thermal initiator is azobisisobutyronitrile; the mass ratio of the thermal initiator to the pentaerythritol tetraacrylate monomer is (0.2-0.3):2.

[0060] In one specific embodiment, the heating temperature is 55-65°C and the time is 8-12 hours.

[0061] When the heating temperature and time parameters are within the above ranges, it ensures that the monomers are fully converted and fully polymerized, which is beneficial to improving the electrolyte ionic conductivity and lithium ion transference number. If the temperature is too low (e.g., 30°C) or the time is too short (e.g., 3 hours), the polymerization may be incomplete, leaving unreacted monomers and affecting the electrolyte performance. If the temperature is too high (e.g., 100°C) or the time is too long (e.g., 20 hours), side reactions may occur, such as excessive cross-linking or decomposition, leading to a decrease in electrolyte performance.

[0062] A third aspect of the present invention provides a high-voltage lithium-ion battery, comprising the aforementioned high-voltage fluorinated polyether gel polymer electrolyte or a high-voltage fluorinated polyether gel polymer electrolyte prepared by the aforementioned preparation method. Research by the present invention shows that the high-voltage lithium-ion battery prepared using the above-mentioned high-voltage fluorinated polyether gel polymer electrolyte exhibits excellent cycle stability and significantly extended lifespan at high cutoff voltages.

[0063] The present invention will be further described below through specific embodiments.

[0064] In the following examples, the lithium salt solution used was formulated as 1M LiPF6 in DEC:DMC:EC=1:1:1 Vol% with 10% FEC, purchased from Aladdin; the molecular weight of the polyethylene glycol monomethyl ether methacrylate monomer used was 320 g / mol.

[0065] Example 1 (The mass ratio of PETEA, PEGMA and PFMA is 2:1:2)

[0066] The high-pressure fluorinated polyether gel polymer electrolyte provided in this embodiment is obtained by a preparation method including the following process:

[0067] S1. In an argon glove box, 1.8g of lithium salt solution, 0.08g of pentaerythritol tetraacrylate monomer (PETEA), 0.04g of polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), 0.08g of 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA), and 0.01g of azobisisobutyronitrile (AIBN) were sequentially added to a glass bottle and stirred at room temperature for 30 minutes until homogeneous, to obtain precursor solution A; wherein the total mass of PETEA, PEGMA, and PFMA is 0.2g, and the mass ratio of PETEA, PEGMA, and PFMA is 2:1:2;

[0068] S2. Precursor solution A is heated at 60°C for 10 hours to carry out in-situ polymerization reaction, and high-pressure fluorinated polyether gel polymer electrolyte is obtained.

[0069] Comparative Example 1 (the mass ratio of PETEA, PEGMA, and PFMA was 2:2:1)

[0070] The polymer electrolyte provided in this comparative example is basically the same as that in Example 1, except that:

[0071] S1. In an argon glove box, 1.8g of lithium salt solution, 0.08g of pentaerythritol tetraacrylate monomer (PETEA), 0.08g of polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), 0.04g of 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA), and 0.01g of azobisisobutyronitrile (AIBN) were sequentially added to a glass bottle and stirred at room temperature for 30 minutes until homogeneous to obtain precursor solution B; wherein, the total mass of PETEA, PEGMA, and PFMA is 0.2g, and the mass ratio of PETEA, PEGMA, and PFMA is 2:2:1.

[0072] Comparative Example 2 (without PFMA)

[0073] The polymer electrolyte provided in this comparative example is basically the same as that in Example 1, except that:

[0074] S1. In an argon glove box, 1.8g of lithium salt solution, 0.133g of pentaerythritol tetraacrylate monomer (PETEA), 0.067g of polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), and 0.01g of azobisisobutyronitrile (AIBN) were added sequentially to a glass bottle and stirred at room temperature for 30 minutes until homogeneous to obtain precursor solution C; wherein, the total mass of PETEA and PEGMA is 0.2g, and the mass ratio of PETEA to PEGMA is 2:1.

[0075] Comparative Example 3 (without PEGMA)

[0076] The polymer electrolyte provided in this comparative example is basically the same as that in Example 1, except that:

[0077] S1. In an argon glove box, 1.8g of lithium salt solution, 0.04g of pentaerythritol tetraacrylate monomer (PETEA), 0.16g of 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA), and 0.01g of azobisisobutyronitrile (AIBN) were added sequentially to a glass bottle and stirred at room temperature for 30 minutes until homogeneous to obtain precursor solution D; wherein, the total mass of PETEA and PFMA is 0.2g, and the mass ratio of PETEA to PFMA is 1:4.

[0078] Comparative Example 4 (without PETEA)

[0079] The electrolyte provided in this comparative example is basically the same as that in Example 1, except that:

[0080] S1. In an argon glove box, 1.8g of lithium salt solution, 0.04g of polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), 0.16g of 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA), and 0.01g of azobisisobutyronitrile (AIBN) were added sequentially to a glass bottle and stirred at room temperature for 30 minutes until homogeneous to obtain precursor solution E; wherein, the total mass of PEGMA and PFMA is 0.2g, and the mass ratio of PEGMA to PFMA is 1:4.

[0081] During the preparation of the electrolyte in this comparative example, the inventors discovered that the precursor solution E in this comparative example could not be solidified after heating at 60°C for 10 hours, and the resulting electrolyte was in a liquid state, so no subsequent performance tests were performed.

[0082] Comparative Example 5

[0083] This comparative example provides a liquid electrolyte, which is a 2g lithium salt solution.

[0084] Application Example 1

[0085] This application example provides a lithium-ion battery, including:

[0086] Preparation of high-voltage NCM811: The positive electrode active material (NCM811, 80wt%), conductive additive (Super P, 10wt%), and polyvinylidene fluoride binder (PVDF, 10wt%) were mixed and ground for 30 min. Then, N-methylpyrrolidone (NMP) was added and ground evenly to obtain a well-dispersed slurry. The slurry was coated onto carbon-coated aluminum foil and dried in an oven at 80℃ for 2 h, and then placed in a vacuum oven at 120℃ for 12 h to obtain aluminum foil coated with the active material. The aluminum foil coated with the active material was cut into circular pieces with a diameter of 12 mm to obtain high-voltage NCM811.

[0087] In a glove box where the moisture and oxygen content are both below 0.01 ppm, the precursor solution A from Example 1 was added to a battery casing with high-voltage NCM811 as the positive electrode, lithium metal as the negative electrode, and polypropylene as the separator. The casing was then left to stand at 60°C for 10 hours (h) to obtain a lithium-ion battery containing a high-voltage fluorinated polyether gel polymer electrolyte.

[0088] Application Example 2

[0089] The lithium-ion battery provided in this application example is basically the same as that in application example 1, except that the precursor solution A in example 1 is replaced with the precursor solution C in comparative example 2.

[0090] Application Example 3

[0091] This application example provides a lithium-ion battery, including:

[0092] Preparation of high-voltage NCM811: The preparation process is the same as that of high-voltage NCM811 in Application Example 1;

[0093] In a glove box where the moisture and oxygen content were both below 0.01 ppm, 2 g of lithium salt solution from Comparative Example 5 was used as the electrolyte. The electrolyte was added to a battery casing with high-voltage NCM811 as the positive electrode, lithium metal as the negative electrode, and polypropylene as the separator. The casing was then left to stand at 60°C for 10 hours to obtain a lithium-ion battery containing lithium salt solution.

[0094] Performance testing

[0095] 1. Take photographs of the precursor solution A and the high-pressure fluorinated polyether gel polymer electrolyte in Example 1 of this invention, as follows: Figure 2 As shown. Figure 2 These are optical photographs of precursor solution A and high-pressure fluorinated polyether gel polymer electrolyte in Example 1 of the present invention, wherein... Figure 2 A is an optical photograph of precursor solution A. Figure 2 Image B is an optical photograph of a high-pressure fluorinated polyether gel polymer electrolyte.

[0096] Depend on Figure 2 It can be seen that precursor solution A before polymerization ( Figure 2 A) is in a liquid state, but after polymerization ( Figure 2 B) adheres firmly to the wall of the glass bottle, forming a solid gel that effectively encapsulates the lithium salt solution within the gel network structure.

[0097] 2. Disassemble the lithium-ion battery in Application Example 1 and remove the high-voltage fluorinated polyether gel polymer electrolyte, such as... Figure 3 As shown. Figure 3 This is an optical photograph of the high-pressure fluorinated polyether gel polymer electrolyte adhering to the diaphragm in Application Example 1 of the present invention, wherein... Figure 3 A is an optical photograph without bending. Figure 3 B is an optical photograph taken at a 180° bend.

[0098] Figure 3 Results A and B show that the high-pressure fluorinated polyether gel polymer electrolyte has good toughness.

[0099] 3. To verify the successful in-situ polymerization of the high-pressure fluorinated polyether gel polymer electrolyte, infrared spectroscopy and nuclear magnetic resonance (NMR) tests were performed on the pentaerythritol tetraacrylate monomer (PETEA), polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA), and the high-pressure fluorinated polyether gel polymer electrolyte (GPE-F) in Example 1, as well as the polymer electrolyte (GPE) in Comparative Example 2. Figure 4 As shown. Figure 4 The infrared spectroscopy and nuclear magnetic resonance (NMR) results are as follows: Pentaerythritol tetraacrylate monomer (PETEA), polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA), and high-pressure fluorinated polyether gel polymer electrolyte (GPE-F) from Example 1 of this invention, and the polymer electrolyte (GPE) from Comparative Example 2. Figure 4 A represents the infrared spectroscopy test result. Figure 4 B represents the NMR test result.

[0100] Depend on Figure 4 As shown in A and B, pentaerythritol tetraacrylate monomer (PETEA), polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), and 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA) were successfully polymerized to obtain a fluorinated polyether polymer; pentaerythritol tetraacrylate monomer (PETEA) and polyethylene glycol monomethyl ether methacrylate monomer (PEGMA) were successfully polymerized to obtain a polyether polymer.

[0101] 4. To verify the influence of each component in the high-pressure fluorinated polyether gel polymer electrolyte on the formation of the solid electrolyte interphase (SEI) and positive electrode electrolyte interphase (CEI), LUMO and HUMO energy level calculations were performed on each component in the high-pressure fluorinated polyether gel polymer electrolyte of Example 1 of this invention, as follows: Figure 5 As shown. Figure 5 The results show the calculated LUMO and HUMO energy levels of each component in the high-pressure fluorinated polyether gel polymer electrolyte of Example 1 of this invention.

[0102] Depend on Figure 5 It is known that 2-(perfluorobutyl)ethyl methacrylate monomer (PFMA) has a lower LUMO and higher oxidation stability than polyethylene glycol monomethyl ether methacrylate monomer (PEGMA), which is beneficial for the formation of stable SEI and CEI and enhances the cycle stability of the battery.

[0103] 5. The ionic conductivity of the high-voltage fluorinated polyether gel polymer electrolyte in Example 1 of the present invention and the polymer electrolytes in Comparative Examples 1-3 were tested at room temperature. The test results are shown in Table 1.

[0104] Table 1. Results of Ion Conductivity Tests

[0105]

[0106] As shown in Table 1, the high-voltage fluorinated polyether gel polymer electrolyte provided in this embodiment of the invention has a high ionic conductivity, reaching 1.61 × 10⁻⁶. -3 S / cm.

[0107] 6. Electrochemical window (LSV) tests were performed on the high-voltage fluorinated polyether gel polymer electrolyte in Example 1 of the present invention, the polymer electrolytes in Comparative Examples 1-3, and the liquid electrolyte in Comparative Example 5. The test results are shown in Table 2.

[0108] Table 2 Electrochemical window test results

[0109]

[0110] As shown in Table 2, the electrochemical window of the high-voltage fluorinated polyether gel polymer electrolyte provided in the embodiments of the present invention is higher than that of the polymer electrolytes in Comparative Examples 1-3 and the liquid electrolyte in Comparative Example 5, reaching 4.60V, indicating that the high-voltage fluorinated polyether gel polymer electrolyte has a wide electrochemical stability window.

[0111] 7. The lithium-ion transference number of the high-voltage fluorinated polyether gel polymer electrolyte in Example 1, the polymer electrolyte in Comparative Example 2, and the liquid electrolyte in Comparative Example 5 were tested respectively, and the results are shown in Table 3.

[0112] Table 3. Lithium-ion transference number test results

[0113]

[0114] As shown in Table 3, the high-pressure fluorinated polyether gel polymer electrolyte provided in the embodiments of the present invention has a high lithium-ion transference number (t). Li + =0.85).

[0115] 8. Cycle performance tests were conducted on the lithium-ion batteries in Application Examples 1-3 of this invention to evaluate the interfacial stability of the high-voltage fluorinated polyether gel polymer electrolyte. The test results are as follows: Figure 6 As shown, the relevant test results are summarized in Table 4;

[0116] Table 4 Test Results

[0117]

[0118] Figure 6 The lithium-ion batteries in Examples 1-3 of this invention are used at 0.1 mA cm -2 Current density and 0.1 mAh cm⁻¹ -2 Cyclic performance test results under area capacity. (From...) Figure 6 As shown in Table 4, at 0.1 mA cm -2 Current density and 0.1 mAh cm⁻¹ -2 At the area capacity, the lithium-ion battery assembled using the polymer electrolyte of Comparative Example 2 (Application Example 2) short-circuited after 2500 hours of cycling, and the lithium-ion battery assembled using the liquid electrolyte of Comparative Example 5 (Application Example 3) short-circuited after only 1400 hours of cycling. However, the lithium-ion battery assembled using the high-voltage fluorinated polyether gel polymer electrolyte of Example 1 (Application Example 1) exhibited a cycle performance of more than 2900 hours, significantly extending its service life. This indicates that the high-voltage fluorinated polyether gel polymer electrolyte provided in the embodiments of the present invention has excellent interfacial stability.

[0119] 9. The lithium-ion batteries in Application Examples 1-3 of this invention were subjected to cycle performance tests under the following conditions: 30°C, 1C rate, and a test voltage range of 2.5-4.3V. The test results are as follows: Figure 7 As shown, the relevant test results are summarized in Table 5.

[0120] Table 5 Test Results

[0121]

[0122] Figure 7This is a cycle diagram of the lithium-ion batteries used in Application Examples 1-3 of this invention under test conditions of 30°C, a rate of 1C, and a test voltage range of 2.5-4.3V. (From...) Figure 7 As shown in Table 5, at 30°C, 1C current density, and 4.3V cutoff voltage, the lithium-ion battery assembled using the high-voltage fluorinated polyether gel polymer electrolyte of Example 1 (Application Example 1) has an initial discharge capacity of 158.8 mAh / g and a capacity retention rate of 61.3% after 670 cycles; the lithium-ion battery assembled using the polymer electrolyte of Comparative Example 2 (Application Example 2) has an initial discharge capacity of 158.7 mAh / g and a capacity retention rate of 59.6% after 650 cycles; and the lithium-ion battery assembled using the liquid electrolyte of Comparative Example 5 (Application Example 3) has an initial discharge capacity of 140.7 mAh / g and a capacity retention rate of 31% after 200 cycles. These results indicate that the high-voltage fluorinated polyether gel polymer electrolyte provided in this example exhibits superior cycle stability compared to Comparative Examples 2 and 5.

[0123] 10. To further verify the cycle stability of the lithium-ion battery under high voltage conditions, the lithium-ion battery in Application Example 1 of this invention was subjected to cycle performance testing under the following conditions: 30°C, a rate of 1C, and a test voltage range of 2.8-4.5V. The test results are as follows: Figure 8 As shown; the lithium-ion battery in Application Example 1 of this invention was subjected to cycle performance testing under test conditions of 30°C, a rate of 1C, and a test voltage range of 2.8-4.8V. The test results are as follows. Figure 9 As shown.

[0124] Figure 8 The cycling diagram shows the lithium-ion battery in Application Example 1 of this invention under test conditions of 30°C, 1C rate, and a test voltage range of 2.8-4.5V. Figure 9 This is a cycle diagram of the lithium-ion battery in Application Example 1 of this invention under test conditions of 30°C, a rate of 1C, and a test voltage range of 2.8-4.8V. (From...) Figure 8 and Figure 9 It can be seen that, at higher cutoff voltages of 4.5V or 4.8V, the lithium-ion battery assembled using the high-voltage fluorinated polyether gel polymer electrolyte of Example 1 (Application Example 1) still maintains excellent cycle stability after long-term cycling.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-pressure fluorinated polyether gel polymer electrolyte, characterized in that, It includes a fluorinated polyether polymer and a lithium salt and an organic solvent dispersed in the fluorinated polyether polymer; The fluorinated polyether-based polymer is obtained by in-situ polymerization of pentaerythritol tetraacrylate monomer, polyethylene glycol monomethyl ether methacrylate monomer and 2-(perfluorobutyl)ethyl methacrylate monomer.

2. The high-pressure fluorinated polyether gel polymer electrolyte according to claim 1, characterized in that, The mass ratio of the pentaerythritol tetraacrylate monomer, the polyethylene glycol monomethyl ether methacrylate monomer, and the 2-(perfluorobutyl)ethyl methacrylate monomer is 2:1:

2.

3. The high-pressure fluorinated polyether gel polymer electrolyte according to claim 2, characterized in that, The molecular weight of the polyethylene glycol monomethyl ether methacrylate monomer is 200-400 g / mol.

4. A method for preparing a high-pressure fluorinated polyether gel polymer electrolyte according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Dissolve lithium salt in an organic solvent to prepare a lithium salt solution; (2) The lithium salt solution, pentaerythritol tetraacrylate monomer, polyethylene glycol monomethyl ether methacrylate monomer, 2-(perfluorobutyl)ethyl methacrylate monomer and thermal initiator are mixed to obtain a precursor solution; (3) The precursor solution is heated to carry out in-situ polymerization to obtain the high-pressure fluorinated polyether gel polymer electrolyte.

5. The method for preparing high-pressure fluorinated polyether gel polymer electrolyte according to claim 4, characterized in that, In step (1), the lithium salt is lithium hexafluorophosphate, and the organic solvent is at least one of diethyl carbonate, dimethyl carbonate, ethylene carbonate, and fluoroethylene carbonate. The lithium salt solution has a lithium salt concentration of 1 mol / L.

6. The method for preparing high-pressure fluorinated polyether gel polymer electrolyte according to claim 4, characterized in that, In step (2), the mass ratio of the lithium salt solution, the pentaerythritol tetraacrylate monomer, the polyethylene glycol monomethyl ether methacrylate monomer, and the 2-(perfluorobutyl)ethyl methacrylate monomer is 45:2:1:

2.

7. The method for preparing high-pressure fluorinated polyether gel polymer electrolyte according to claim 4, characterized in that, In step (2), the molecular weight of the polyethylene glycol monomethyl ether methacrylate monomer is 200-400 g / mol.

8. The method for preparing high-pressure fluorinated polyether gel polymer electrolyte according to claim 4, characterized in that, In step (2), the thermal initiator is azobisisobutyronitrile; The mass ratio of the thermal initiator to the pentaerythritol tetraacrylate monomer is (0.2-0.3):

2.

9. The method for preparing high-pressure fluorinated polyether gel polymer electrolyte according to claim 4, characterized in that, In step (3), the heating temperature is 55-65℃ and the heating time is 8-12 hours.

10. A high-voltage lithium-ion battery, characterized in that, Includes the high-pressure fluorinated polyether gel polymer electrolyte according to any one of claims 1-3 or the high-pressure fluorinated polyether gel polymer electrolyte prepared by the preparation method according to any one of claims 4-9.

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